diff --git a/src/r_bsp.c b/src/r_bsp.c
index e79a1cee3..f71dea646 100644
--- a/src/r_bsp.c
+++ b/src/r_bsp.c
@@ -425,11 +425,13 @@ boolean R_IsEmptyLine(seg_t *line, sector_t *front, sector_t *back)
 
 boolean R_IsDebugLine(seg_t *line)
 {
-	if (line->linedef->special == 2001) // Ring Racers: Finish Line
+	if (cv_debugfinishline.value)
 	{
-		if (cv_debugfinishline.value)
+		switch (line->linedef->special)
 		{
-			return true;
+			case 2001: // Ring Racers: Finish Line
+			case 2003: // Ring Racers: Respawn Line
+				return true;
 		}
 	}
 
diff --git a/src/r_debug.cpp b/src/r_debug.cpp
index 8fbe9390d..bb7590a5c 100644
--- a/src/r_debug.cpp
+++ b/src/r_debug.cpp
@@ -15,6 +15,7 @@
 #include "r_debug_detail.hpp"
 
 #include "command.h"
+#include "i_time.h"
 #include "m_fixed.h"
 #include "r_draw.h"
 #include "r_main.h"
@@ -72,6 +73,22 @@ INT32 R_AdjustLightLevel(INT32 light)
 	return light / FRACUNIT;
 }
 
+UINT8 R_DebugLineColor(const line_t *ld)
+{
+	const bool alt = (I_GetTime() % 70 < 35);
+
+	switch (ld->special)
+	{
+	case 2001: // Ring Racers: Finish Line
+		return alt ? 0x1F : 0x49; // black, yellow
+
+	case 2003: // Ring Racers: Respawn Line
+		return alt ? 0x23 : 0x00; // red, white
+	}
+
+	return 0x00;
+}
+
 void Command_Debugrender_highlight(void)
 {
 	const bool changes = COM_Argc() > 1;
diff --git a/src/r_main.h b/src/r_main.h
index 40103561a..62d6cd1d3 100644
--- a/src/r_main.h
+++ b/src/r_main.h
@@ -142,6 +142,7 @@ extern UINT32 debugrender_highlight;
 
 void R_CheckDebugHighlight(debugrender_highlight_t type);
 INT32 R_AdjustLightLevel(INT32 light);
+UINT8 R_DebugLineColor(const line_t *ld);
 
 void Command_Debugrender_highlight(void);
 
diff --git a/src/r_segs.c b/src/r_segs.c
index 00ab6348b..f671241cf 100644
--- a/src/r_segs.c
+++ b/src/r_segs.c
@@ -500,6 +500,52 @@ static void R_RenderMaskedSegLoop(drawseg_t *ds, INT32 x1, INT32 x2, INT32 texnu
 	}
 }
 
+static void R_RenderMaskedSegLoopDebug(drawseg_t *ds, INT32 x1, INT32 x2, void (*colfunc_2s)(column_t *, column_t *, INT32))
+{
+	column_t *col;
+
+	dc_lightmap = scalelight[LIGHTLEVELS - 1][0]; // max brightness
+
+	// draw the columns
+	for (dc_x = x1; dc_x <= x2; dc_x++)
+	{
+		if (maskedtexturecol[dc_x] != INT16_MAX)
+		{
+			dc_texturemid = ds->maskedtextureheight[dc_x];
+
+			if (R_OverflowTest())
+			{
+				spryscale += rw_scalestep;
+				continue;
+			}
+
+			sprtopscreen = centeryfrac - FixedMul(dc_texturemid, spryscale);
+			dc_iscale = 0xffffffffu / (unsigned)spryscale;
+
+			col = (column_t *)((UINT8 *)R_GetColumn(g_texturenum_dbgline, maskedtexturecol[dc_x]) - 3);
+			colfunc_2s(col, NULL, -1);
+		}
+
+		spryscale += rw_scalestep;
+	}
+}
+
+static INT32 R_GetTwoSidedMidTexture(seg_t *line)
+{
+	INT32 texture;
+
+	if (R_IsDebugLine(line))
+	{
+		texture = g_texturenum_dbgline;
+	}
+	else
+	{
+		texture = line->sidedef->midtexture;
+	}
+
+	return R_GetTextureNum(texture);
+}
+
 static boolean R_CheckBlendMode(const line_t *ldef, INT32 bmnum)
 {
 	transnum_t transtable = NUMTRANSMAPS;
@@ -549,10 +595,10 @@ static boolean R_CheckBlendMode(const line_t *ldef, INT32 bmnum)
 
 void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 {
-	INT32 texnum, bmnum, i;
+	INT32 texnum, bmnum;
 	void (*colfunc_2s)(column_t *, column_t *, INT32);
 	line_t *ldef;
-	INT32 range;
+	const boolean debug = R_IsDebugLine(ds->curline);
 
 	// Calculate light table.
 	// Use different light tables
@@ -560,35 +606,9 @@ void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 	// OPTIMIZE: get rid of LIGHTSEGSHIFT globally
 	curline = ds->curline;
 
-	if (R_IsDebugLine(curline))
-	{
-		const UINT8 thickness = 4;
-		const UINT8 pal = (leveltime % 70 < 35) ? 0x23 : 0x00;
-
-		const INT32 horizon = ((centeryfrac>>4) + 1 + HEIGHTUNIT - 1) >> HEIGHTBITS;
-		const INT32 y = max(0, min(horizon, vid.height - thickness));
-
-		UINT8 *p = &topleft[x1 + (y * vid.width)];
-
-		range = max(x2 - x1, 0) + 1;
-
-		for (i = 0; i < thickness; ++i)
-		{
-			memset(p, pal, range);
-			p += vid.width;
-		}
-
-		return;
-	}
-
-	if (ds->maskedtexturecol == NULL)
-	{
-		return;
-	}
-
 	frontsector = curline->frontsector;
 	backsector = curline->backsector;
-	texnum = R_GetTextureNum(curline->sidedef->midtexture);
+	texnum = R_GetTwoSidedMidTexture(curline);
 	bmnum = R_GetTextureBrightmap(texnum);
 	windowbottom = windowtop = sprbotscreen = INT32_MAX;
 
@@ -596,7 +616,7 @@ void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 
 	R_CheckDebugHighlight(SW_HI_MIDTEXTURES);
 
-	if (R_CheckBlendMode(ldef, bmnum) == false)
+	if (debug == false && R_CheckBlendMode(ldef, bmnum) == false)
 	{
 		return; // does not render
 	}
@@ -632,7 +652,16 @@ void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 	mfloorclip = ds->sprbottomclip;
 	mceilingclip = ds->sprtopclip;
 
-	R_RenderMaskedSegLoop(ds, x1, x2, texnum, bmnum, colfunc_2s);
+	if (debug)
+	{
+		colfunc = R_DrawColumn_Flat_8;
+		r8_flatcolor = R_DebugLineColor(ldef);
+		R_RenderMaskedSegLoopDebug(ds, x1, x2, colfunc_2s);
+	}
+	else
+	{
+		R_RenderMaskedSegLoop(ds, x1, x2, texnum, bmnum, colfunc_2s);
+	}
 
 	R_SetColumnFunc(BASEDRAWFUNC, false);
 }
@@ -1694,6 +1723,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 	vertex_t segleft, segright;
 	fixed_t ceilingfrontslide, floorfrontslide, ceilingbackslide, floorbackslide;
 	static size_t maxdrawsegs = 0;
+	const INT32 twosidedmidtexture = R_GetTwoSidedMidTexture(curline);
 
 	maskedtextureheight = NULL;
 	//initialize segleft and segright
@@ -2411,7 +2441,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 
 			ds_p->numthicksides = numthicksides = i;
 		}
-		if (sidedef->midtexture > 0 && sidedef->midtexture < numtextures)
+		if (twosidedmidtexture)
 		{
 			// masked midtexture
 			if (!ds_p->thicksidecol)
@@ -2462,6 +2492,17 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 			rw_midtexturemid += sidedef->rowoffset;
 			rw_midtextureback += sidedef->rowoffset;
 
+			if (R_IsDebugLine(curline))
+			{
+				// Line draws at horizon
+				rw_midtexturemid = 0;
+				rw_midtextureback = 0;
+
+				// Ignore slopes
+				rw_midtextureslide = 0;
+				rw_midtexturebackslide = 0;
+			}
+
 			maskedtexture = true;
 		}
 	}
@@ -2943,12 +2984,12 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 	if (maskedtexture && !(ds_p->silhouette & SIL_TOP))
 	{
 		ds_p->silhouette |= SIL_TOP;
-		ds_p->tsilheight = (sidedef->midtexture > 0 && sidedef->midtexture < numtextures) ? INT32_MIN: INT32_MAX;
+		ds_p->tsilheight = twosidedmidtexture ? INT32_MIN: INT32_MAX;
 	}
 	if (maskedtexture && !(ds_p->silhouette & SIL_BOTTOM))
 	{
 		ds_p->silhouette |= SIL_BOTTOM;
-		ds_p->bsilheight = (sidedef->midtexture > 0 && sidedef->midtexture < numtextures) ? INT32_MAX: INT32_MIN;
+		ds_p->bsilheight = twosidedmidtexture ? INT32_MAX: INT32_MIN;
 	}
 	ds_p++;
 }
diff --git a/src/r_textures.c b/src/r_textures.c
index 2f36fca08..5d3669b11 100644
--- a/src/r_textures.c
+++ b/src/r_textures.c
@@ -57,6 +57,8 @@ fixed_t *textureheight; // needed for texture pegging
 INT32 *texturetranslation;
 INT32 *texturebrightmaps;
 
+INT32 g_texturenum_dbgline;
+
 // Painfully simple texture id cacheing to make maps load faster. :3
 static struct {
 	char name[9];
@@ -1126,6 +1128,8 @@ static void R_FinishLoadingTextures(INT32 add)
 	if (rendermode == render_opengl)
 		HWR_LoadMapTextures(numtextures);
 #endif
+
+	g_texturenum_dbgline = R_CheckTextureNumForName("DBGLINE");
 }
 
 //
diff --git a/src/r_textures.h b/src/r_textures.h
index 066b10fbd..084447faa 100644
--- a/src/r_textures.h
+++ b/src/r_textures.h
@@ -114,6 +114,8 @@ void R_PrintTextureDuplicates(void);
 
 extern INT32 numtextures;
 
+extern INT32 g_texturenum_dbgline;
+
 #ifdef __cplusplus
 } // extern "C"
 #endif
diff --git a/src/r_things.c b/src/r_things.c
index c8ef9b557..70fc44923 100644
--- a/src/r_things.c
+++ b/src/r_things.c
@@ -2899,7 +2899,7 @@ static void R_CreateDrawNodes(maskcount_t* mask, drawnode_t* head, boolean temps
 			}
 			ds->curline->polyseg->visplane = NULL;
 		}
-		if (ds->maskedtexturecol || R_IsDebugLine(ds->curline))
+		if (ds->maskedtexturecol)
 		{
 			entry = R_CreateDrawNode(head);
 			entry->seg = ds;
@@ -3698,10 +3698,11 @@ static void R_DrawMaskedList (drawnode_t* head)
 			R_DoneWithNode(r2);
 			r2 = next;
 		}
-		else if (r2->seg)
+		else if (r2->seg && r2->seg->maskedtexturecol != NULL)
 		{
 			next = r2->prev;
 			R_RenderMaskedSegRange(r2->seg, r2->seg->x1, r2->seg->x2);
+			r2->seg->maskedtexturecol = NULL;
 			R_DoneWithNode(r2);
 			r2 = next;
 		}